Equis ISSN 2398-2977

Rectum: prolapse

Contributor(s): Roberta Baxter, David Moll, Graham Munroe

Introduction

  • Rectal prolapse is relatively rare in the horse.
  • Signs: protrusion of the rectal mucosa through the anal sphincter.
  • Cause: usually a sequel to excessive straining due to other disease.
  • Diagnosis: clinical signs.
  • Treatment: manual reduction and medical treatment where possible, and surgical resection/euthanasia in severe cases.
  • Prognosis: depends on extent of prolapse.

Pathogenesis

Etiology

  • Any condition causing excessive straining or tenesmus.

Predisposing factors

General

Specific

  • Loss of tone in the anal sphincter.
  • Loose attachments of the mucous membrane to the muscular coat of the rectum.
  • Loose attachments of the rectum to the perirectal tissues.

Pathophysiology

  • Excessive straining causes prolapse of rectum through anus.
  • This may be mucosal only, or may be complete with colonic invagination.
  • Secondary mucosal edema, vascular compromise and necrosis occur rapidly due to anal ring constriction.
  • Reduced blood supply to the prolapsed section of bowel → devitalization of the bowel wall. This can be very mild, resulting merely in inflammation and edema, or may be more serious → bowel compromise and necrosis.
  • In mild cases, partial bowel obstruction causes distension and pain of more proximal bowel, and this, together with inflammation stimulates further straining which can lead to further prolapse, or the development of an intussusception.
  • In severe/prolonged cases, venous drainage of the area is impaired resulting in swelling, edema, and congestion. There may be progressive arterial obstruction, which can cause ischemia of the prolapsed tissue. Progressive ischemia and disruption of the mucosal layers, can lead to necrosis and cell sloughing.
  • In rare cases endotoxemia and consequent cardiovascular signs may develop.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Gibson K, O'Hara A & Huxtable C (2001) Focal eosinophilic proctitis with associated rectal prolapse in a pony. Aust Vet J 79 (10), 679-681 PubMed.
  • Ragle C A et al (1997) Laparoscopic diagnosis of ischemic necrosis of the descending colon after rectal prolapse and rupture of the mesocolon in two postpartum mares. J Am Vet Med Assoc 210 (11), 1646-1648 PubMed.
  • Abd El Karim R (1995) Two cases of rectal prolapse in the donkey. Equine Vet Educ (1), 12-14 VetMedResource.
  • Rick M C (1989) Management of rectal injuries. Vet Clin North Am Equine Pract 5 (2), 407-428 PubMed.


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